Will this work???

My name is Caroline. In college I want to be called Caris. (keri-is) Will it work? Many similar letters! I look and feel more like a Caris than a Caroline! Plus, it's a smosh of my name and Paris, a name I've always loved more than anything. You like it or think it's stupid? BE HONEST!

As a nickname for Caroline, I think it does. The beginning parts sound similar. I swore I read somewhere that there was a character on a telenovela where a character named Regina went by Regis. Caroline to Caris seems to be in a similar vein.

"Don't try to be modern, it's the most old-fashioned thing there is," - Attilio, The Tiger and the Snow

I think it works as a nn for Caroline. Just make sure you introduce yourself always as Caris first so people get it. My name is AlexandraLee and I go by Andie which is also a bit of a stretch but I always introduce myself as Andie and most people assume my name is Andrea not Alexandra. I haven't had a problem with anyone not calling me by my chosen nn. Best of luck to you!